Machine for the production of sheet elements from composite material

ABSTRACT

The machine has a heated plate, a conveyor for conveying the elements along a conveyor path leading across the heated plate, a top part vertically movable with respect to the heated plate, a membrane disposed on the top part and a separating film disposed between the membrane and the heated plate which can be moved synchronously with the conveyor. The separating film is divided into sections and every section is retained exclusively by a single edge oriented transversely to the conveying path by a retaining device. The sections therefore sit loosely on the elements free of tension. The membrane lies against a peripherally extending peripheral face of the top part facing the heated plate and can be moved directly onto the plane of the surface of the heated plate in order to form a closed chamber with it. Finally, the membrane is connected to a clamping device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and Applicant claims priority under35 U.S.C. §§120 and 121 of parent U.S. patent application Ser. No.11/921,488 filed on Aug. 31, 2009, which application is a national stageapplication under 35 U.S.C. §371 of PCT/EP2006/005221 filed on Jun. 1,2006, which claims priority under 35 U.S.C. §119 of Swiss ApplicationNo. 0950/05 filed on Jun. 3, 2005, the disclosures of each of which arehereby incorporated by reference. The international application underPCT article 21(2) was not published in English.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a machine for producing board-shaped elementsof composite material, with a heated plate, conveyor means fortransporting the elements along a conveyor path running above the heatedplate, a top part which can be moved vertically with respect to theheated plate, a membrane disposed on the top part and a separating filmdisposed between the membrane and the heated plate which can be movedsynchronously with the conveyor means.

2. The Prior Art

When producing board-shaped elements made from composite material, forexample photovoltaic elements, several layers, including glass amongstothers, are assembled under the effect of pressure and heat. Themachines needed for this process generally have a heatable laminatingstation, a cooling station and conveying means for intermittentlyconveying the elements. The laminating station has a heated plate and atop part which can be lowered onto the heated plate, and a membrane isprovided which forms a closed chamber in conjunction with the heatedplate in the lowered state. By evacuating this chamber, gas can beremoved from around the elements and the membrane is applied to theheated plate due to the pressure acting on the side of the membranefacing away from the chamber so that the elements are pressed together.

In terms of conveying means for the elements, known means comprise aconveyor belt, which simultaneously protects the heated plate againstdirt, for example adhesive spilling out of the elements. In order toprotect the vacuum membrane as well, a known approach is to provide aseparating film for the elements, covering their top surface. Both theconveyor belt and the separating film may be used in the form of endlesswebs. The disadvantage of this is that control mechanisms have to beprovided in order to ensure that the webs do not run sideways off therollers conveying and turning the webs. Instead of using endless webs, aknown way of avoiding this problem is to use sections which are conveyedby means of traction elements, for example chains, disposed to the sideof the displacement path. This being the case, the sections areinter-connected by spring elements to form an endless loop. Due to thespring elements, the sections are subjected to tensile stress in theconveying direction, which causes the sections of separating film lyingon top to lift off the elements as soon as the pressing force isremoved. Any adhesive which leaks out between the separating film andthe elements exerts a force directed upwards towards the elements, whichis particularly problematic in the laminating station because theadhesive between the layers of elements has not yet set at this stage.

In the case of many known machines, the membrane is clamped in a frame,which is in turn sealed with respect to the heated plate and its edge bymeans of a peripherally extending seal when the press is closed. Apartfrom the extra work needed to produce the frame and the seal, thedisadvantage of this approach is the fact that the membrane is subjectedto high tensile forces in the region of the frame during the pressingoperation. Tearing of the membrane during the pressing operation cancause damage to the elements to be laminated. During operation, themembrane is exposed to high temperature fluctuations, as a result ofwhich it expands and contracts again with every work cycle. If themembrane is retained in the frame too loosely, there is a tendency forcreases to form and it has to be tautened again. The job of subsequenttautening takes time because the frame has to be dismantled and thenscrewed back down again after tautening.

SUMMARY OF THE INVENTION

The underlying objective of the invention is to propose a laminatingmachine which does not have the disadvantages outlined above.

This objective is achieved by the invention due to the fact that theseparating film is divided into sections, every section is held byretaining means exclusively at a single edge oriented transversely tothe conveying path, the sections are not connected to one another andthe retaining means can be moved along the conveying path by drivemeans.

The advantages of this solution reside in the fact that the separatingfilm conforms efficiently to the shape of the elements to be laminatedbecause it lies loosely on the elements and the separating film is notstretched when the press is opened, which means that no force istransmitted by the separating film to the elements. Also as a result ofthe invention, a saving is made on components and the work involved ininter-connecting the sections of separating film which has to be carriedout in the case of known machines is dispensed with.

In one embodiment of the invention, the drive means have peripherallyextending traction means, in particular chains. These traction means maybe guided next to the heated plate and can be easily synchronized withthe conveyor means.

In another embodiment, the sections are guided in a circle by pulleymeans, and in a region where the sections are guided essentiallyvertically in a downward direction, guides in the form of brushes areprovided, with bristles oriented towards at least one of the twosurfaces of the sections. Without these guides, the sections of theseparating film at the rear as viewed in the conveying direction, whichare effectively held by the retaining means at the front end only, dropdownwards in this region and prevent the elements from getting into themachine.

In another embodiment, the retaining means have a C-shaped section, intothe lengthways orifice of which a closed loop of the section extends, inwhich an anchoring bar is accommodated, the diameter of which is biggerthan the width of the orifice. These retaining means are particularlysimple and inexpensive to manufacture and also ensure that the sectionsof separating film are secured without creases.

By virtue of another aspect of the invention, the objective is achieveddue to the fact that the membrane lies against a peripherally extendingperipheral surface of the top part facing the heated plate, the membranecan be fitted on the surface of the heated place or its edge in anarrangement which provides a seal with the region of its surface lyingopposite the peripheral surface to prevent excessive external pressureand the membrane is connected to clamping means disposed on the toppart.

A major advantage of this solution resides in the fact that the membraneitself provides the seal on the heated plate forming a closed chamber inconjunction with it, with the separating film and optionally theconveying means inserted in between but without a frame incorporating anadditional seal. During the pressing operation, therefore, few tensileforces act on the membrane because the zone in which the membrane isclamped is disposed on a level with the heated plate and not above theheated plate, as is the case with the prior art. The maximum tensileforce in the membrane does not therefore occur until the press isopened, so that any tearing of the membrane which might occur does notcause damage to the laminated elements. Furthermore, a pre-definedclamping action can be obtained and maintained in the membrane by theclamping means, thereby avoiding excessive strain and creases in themembrane.

In one embodiment, the clamping means are connected to the membrane bymeans of clamp mechanisms. The clamp mechanisms enable the membrane tobe held and clamped without having to provide holes in its edge, whichcan tear open in a known manner.

In another embodiment, every clamp mechanism comprises two clamping jawswhich can be clamped to one another by screws and which havelongitudinally disposed recesses and clamp the membrane between them,and a section deflecting the membrane is placed in at least one of therecesses. These inexpensive features enable the membrane to be securedparticularly reliably without excessive strain, due to a strong pinchingaction.

In another embodiment, the clamping means contain a mechanism whichgenerates at least one force. Other than a mechanism which stores aforce, such as a spring, a device such as a servo-motor may be used togenerate a force, which maintains a constant clamping action even in theevent of big changes to the length of the membrane.

In another embodiment, the device generating the force ispiston-cylinder unit. Such a unit saves on space and is particularlyeasy to operate.

In another embodiment, finally, the device generating the force isconnected to the membrane via traction means. This feature enables thedevice generating the force to be positioned where space is leftavailable on the machine.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail below with reference toexamples of embodiments illustrated in the appended drawings.

Of these:

FIG. 1 is a schematically illustrated longitudinal section through anembodiment of the machine proposed by the invention,

FIG. 2 shows a detail from FIG. 1 on a larger scale than in FIG. 1,

FIG. 3 shows the same detail as FIG. 2 but in a different operatingmode,

FIG. 4 shows an embodiment of the retaining means for the separatingfilm,

FIG. 5 shows an embodiment of the clamping means for the membrane and

FIG. 6 shows a detail from a machine of the type known from the priorart.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Firstly, it should be pointed out that the same parts described in thedifferent embodiments are denoted by the same reference numbers and thesame component names and the disclosures made throughout the descriptioncan be transposed in terms of meaning to same parts bearing the samereference numbers or same component names, Furthermore, the positionschosen for the purposes of the description, such as top, bottom, side,etc. relate to the drawing specifically being described and can betransposed in terms of meaning to a new position when another positionis being described.

The embodiments illustrated as examples represent possible designvariants of the machine and it should be pointed out at this stage thatthe invention is not specifically limited to the design variantsspecifically illustrated, and instead the individual design variants maybe used in different combinations with one another and these possiblevariations lie within the reach of the person skilled in this technicalfield given the disclosed technical teaching. Accordingly, allconceivable design variants which can be obtained by combiningindividual details of the design variants described and illustrated arepossible and fall within the scope of the invention.

For the sake of good order, finally, it should be pointed out that, inorder to provide a clearer understanding of the structure of themachine, it and its constituent parts are illustrated to a certainextent out of scale and/or on an enlarged scale and/or on a reducedscale.

FIG. 1 is a highly simplified schematic diagram showing a view insection through the longitudinal axis of one embodiment of a machine 1proposed by the invention. The machine is naturally mounted in a frame,although this is not illustrated in order to retain clarity. In themachine, board-shaped elements 4, such as photovoltaic elements, areconveyed by a conveyor means 6 into a laminating station 2, where theelements 4 are laminated under the effect of pressure and heat. Theelements 4 are then conveyed by the conveyor means 6 in the direction ofarrow 31 to a cooling station 3, where they remain under pressure for acertain period of time. The laminating station 2 essentially comprises aheated plate 5 and a top part 8 which can be moved vertically withrespect to it. Reference 12 denotes lifting drives, by means of whichthe top part 8 can be lowered and raised relative to the heated plate 5.On its bottom face, the top part 8 bears a membrane 9, which forms aclosed chamber with the heated plate 5 which can be evacuated when thetop part 8 is in the lowered state. When the chamber is evacuated, theelements 4 to be laminated are pressed by the membrane 9 against theheated plate 5 and any air inclusions which might still exist betweenthe layers of elements 4 are removed and adhesive disposed between thelayers of elements 4 is activated due to the pressure and/or the heat. Achamber 16 is formed in the top part 8 between the membrane 9 and anintermediate wall 14, to which a negative pressure or a positivepressure can be applied in order either to raise the membrane 9 or pushit down. A cavity 13 provided in the top part communicates with thechamber 16 via orifices 15 disposed in the intermediate wall 14.

The cooling station 3 essentially comprises a cooling plate 21 and a toppart 28 which can be moved relative to it by means of lifting drives 22and which, like the top part 8 of the laminating station 2, likewisebears a membrane 29.

The conveyor means 6 in this example are provided in the form ofrectangular sections 7 of flat, flexible material, which are retainedboth by the front edge in the conveying direction 31 and at the rearedge in the conveying direction by retaining means 23. The retainingmeans 23 of two adjacent sections 7 of the conveyor means 6 areconnected to one another by springs 24 so that the conveyor means 6forms an endless loop guided around pulley blocks 18, the re-circulatingstrand of which is guided underneath the cooling plate 21 and the heatedplate 5.

A separating film 10 is laid without any tension on every element 4 orgroup of elements 4 at the intake end 30 into the machine 1, on the onehand in order to protect the membrane 9 from soiling, for example due toadhesive spilling out of the elements 4, and on the other hand toprevent any force, which might occur in particular when opening thelaminating station 2, from causing a relative movement between theindividual layers of elements 4. Every section of the separating film 10is retained at a leading edge in the conveying direction 31, orientedperpendicular to the conveying direction by retaining means 32, in theform of a section in the embodiment illustrated as an example here,which is moved along the conveyor path by a traction means drive, forexample a chain, disposed at both ends of the conveyor path. Theretaining means 32 will be described in more detail below with referenceto FIG. 4. The other edges of the sections 11 of separating film 10 arefree, so that every section lies loosely on the elements 4 as it isconveyed through the machine 1. This is of particular advantage on therun leading away from the laminating station 2 to the cooling station 3because the elements 4 are still hot here and the adhesive joining theindividual layers has not yet set and is therefore sticky and has atendency to flow. If the separating film were tensioned on this run, asis the case with the machines known from the prior art mentioned above,this could lead to an undesired relative movement between the layers.The other advantage which this arrangement has over that known from theprior art is that a retaining means can be dispensed with on one sidefor each section of the separating film 10 and the springs connectingthe sections can be dispensed with altogether. The traction means drivemoving the retaining means 32 runs in a circle and the sections 11 ofseparating film 10 are guided by means of pulley blocks 17, as a resultof which they are fed above the top parts 28 respectively 8 of thecooling station 3 and laminating station 2 back to the intake end 30 ofthe machine 1, on the left-hand side in FIG. 1. Guides may be providedabove the machine (not illustrated), across which the free end 19 ofevery section of the separating film 10 is dragged. In order to preventthe sections 11 from simply falling in the region in which they are fedback in an essentially vertical direction with respect to the intake end30, guides are provided there in the form of elongate brushes 20oriented in the conveying direction 31. Rigid guides disposed on bothfaces of the separating film 10 would be inappropriate because theywould then have to be separated from one another by a space to enablethe retaining means 32 to pass through between them. Depending on thestiffness of the separating film 10, the latter would be able to foldbackwards and forwards between the guides in this space, therebyundesirably leading to bending. By contrast, the brushes on the twosides of the separating film 10 may reach as far as its top surface,because their bristles flex, thereby enabling the retaining means 32 topass by without any difficulty.

Although these are not illustrated, cleaning mechanisms may be providedon the run on which the conveyor means 6 and the separating film 10 aredirected on leaving the cooling station 3 back to the intake end 30 ofthe machine 1, by means of which any soiling such as adhesive residuesmay be removed from the conveyor means 6 and separating film 10. Asclearly illustrated in FIG. 1, the conveyor means 6 and the separatingfilm 10 do not have to be of the same length, For example, theseparating film 10 may perfectly easily have one or more sections thanthe conveyor means 6.

FIG. 2 is a detail from FIG. 1 on a larger scale illustrating thelaminating station 2 in the opened position, in other words with the toppart 8 raised. The element 4 to be laminated is positioned on the heatedplate 5 with a section 7 of the conveyor means disposed in between andcovered by means of a section 11 of the separating film. As may be seenfrom this drawing, the retaining means 32 of section 11, the retainingmeans 23 of section 7 and the springs 24 which interconnect the sections23 are positioned so that they are clamped by the top part 8 as it ismoved downwards. The retaining means 32 of section 11 and the retainingmeans 23 of section 7 are offset from one another in the conveyingdirection so that they do not lie on top of one another. The membrane 9is guided around the edges 46 of the top part 8, and a seal 34 may beinserted between the membrane 9 and the top part 8. The edges of themembrane 9 are held by means of a clamp mechanism 33 which co-operateswith a clamp drive 25. The clamp drive 25 is advantageously provided inthe form of a hydraulically or pneumatically driven piston-cylinderunit. In order to save on space, it is of advantage if the clamp drive25 is disposed above on the top part 8 and its force is transmitted tothe clamp mechanisms 33 via traction means 26, for example Bowden cablesfed by pulley blocks 27, for example. The clamp drive 25 enables apre-defined tension to be maintained in the membrane 9. To this end, itmay be connected to the control system of the machine.

FIG. 3 illustrates the laminating station closed, in other words the toppart 8 has been lowered by means of the lifting drive 12 until theperipherally extending bottom edge 46 presses the seal 34, the membrane9, the section 11 of separating film and the section 7 of the conveyormeans 6 in a sealing arrangement against the heated plate 5 and its edgelying at the same level. As a result, a closed chamber 35 is formedbetween the heated plate 5 and the membrane 9, in which the elements 4to be laminated are disposed. This chamber 35 is now evacuated so thatgas is removed from around the elements 4 and the membrane 9 liestightly on the elements 4 whilst section 11 of the separating film 10lies loosely on top of them.

FIG. 4 illustrates an example of an embodiment of the retaining means 32of section 11 of the separating film 10 on a larger scale than in thepreceding drawings. Section 11 of the separating film 10 is providedwith a loop 36 at a single edge, which may be formed by folding it overand welding, adhering or stitching. This loop 36 is retained in thelengthways orifice of a C-shaped section 37 by means of an anchoring bar38, the diameter of which is bigger than the width of said orifice. Theanchoring bar is advantageously of a tubular shape.

FIG. 5 illustrates the clamp mechanism for the membrane 9 on an evenlarger scale than illustrated in FIGS. 2 and 3 above. The membrane 9 isclamped between two clamping jaws 39 and 40, of which clamping jaw 39 isconnected to the traction means 26, although this is not illustrated. Inorder to improve the hold of the membrane 9 in the clamp mechanism 33,the clamping jaw 40 is also provided with longitudinally extendingrecesses in which the fitting sections 42 fit. The clamping jaw 39 alsohas recesses in the region of the fitting sections, so that the membrane9 is bent round on clamping, which significantly increases frictionresistance to being torn out. Screws 41 are used to clamp the clampingjaws 39 and 40 together.

FIG. 6 is a schematic diagram showing a detail of a laminating press ofthe type known from the prior art. The membrane 9 is secured by means ofa clamping frame 43 attached to the top part 8. The clamping frame 43 isfixedly screwed to a flange of the top part by means of screws 45 whichare inserted through holes provided in the membrane 9. In order to sealthe frame 43 on the heated plate 5 and its edge, it is necessary toprovide a seal 44 in the clamping frame 43.

List of reference numbers 1 Machine 2 Laminating station 3 Coolingstation 4 Board-shaped element 5 Heated plate 6 Conveyor means 7 Sectionof 6 8 Top part of 2 9 Membrane 10 Separating film 11 Section of 10 12Lifting drive for 8 13 Cavity in 8 14 Intermediate wall of 8 15 Orificein 14 16 Chamber 17 Pulley block for 10 18 Pulley block for 6 19 Freeend of 10 20 Brushes 21 Cooling plate 22 Lifting drive for 28 23Retaining means for 6 24 Spring 25 Clamp drive 26 Traction means 27Pulley block 28 Top part of 3 29 Membrane 30 Intake end 31 Conveyormechanism 32 Retaining means for 11 33 Clamp mechanism 34 Seal 35Chamber 36 Loop 37 C-section 38 Bar 39 Clamping jaw 40 Clamping jaw 41Screw 42 Fitting section 43 Clamping frame 44 Seal 45 Screw 46Peripheral surface

1. A machine for producing board-shaped elements of composite materialcomprising: (a) a heated plate comprising a heated plate surface and aheated plate edge; (b) a conveyor for conveying the elements along aconveyor path leading across the heated plate; (c) a top part verticallymovable relative to the heated plate and comprising a peripherallyextending peripheral surface facing the heated plate; (d) at least oneclamping device disposed on the top part generating a force; (e) amembrane connected to the at least one clamping device, said membranebeing disposed against the peripheral surface of the top part and havinga membrane surface lying opposite to the peripheral surface sealed onthe heated plate surface or on the heated plate edge; and (f) aseparating film disposed between the membrane and the heated plate andmovable synchronously with the conveyor.
 2. The machine as claimed inclaim 1, wherein the at least one clamping device is connected to themembrane by clamp mechanisms.
 3. The machine as claimed in claim 2,wherein every clamp mechanism comprises two clamping jaws which can beclamped to one another by screws and have longitudinally disposedrecesses and clamp the membrane between the clamping jaws, and adeflector section deflecting the membrane is inserted in at least one ofthe recesses.
 4. The machine as claimed in claim 1, wherein the at leastone clamping device comprises a piston cylinder unit.
 5. The machine asclaimed in claim 1, wherein the at least one clamping device isconnected to the membrane via a traction device.